Windows Update is failing to install “Feature Pack for Windows Azure Pack Web Sites v2 (KB2927682)” on one of my Azure Pack servers. And just give the error message: 0x80070643

The event log shows a slightly better error message; “Product: Web Sites Local Feed — A newer version of Web Sites Local Feed was found on this machine.”

After further investigation, the MSI Logfile reveals some great information and clues;

It lists a program with GUID {BE2AD1F0-C5FF-4F62-95BD-44C829150573} that prevents the installation from completing.
And that GUID turned out, after a quick Registry search, to be “Web Sites MBCA 2.0 Model”.

And after uninstalling “Web Sites MBCA 2.0 Model” from Add/Remove Programs, my Windows Update installation went through at once!